File xsa237-2.patch of Package xen.6121

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File xsa237-2.patch of Package xen.6121

From: Jan Beulich <jbeulich@suse.com>
Subject: x86: enforce proper privilege when (un)mapping pIRQ-s

(Un)mapping of IRQs, just like other RESOURCE__ADD* / RESOURCE__REMOVE*
actions (in FLASK terms) should be XSM_DM_PRIV rather than XSM_TARGET.
This in turn requires bypassing the XSM check in physdev_unmap_pirq()
for the HVM emuirq case just like is being done in physdev_map_pirq().
The primary goal security wise, however, is to no longer allow HVM
guests, by specifying their own domain ID instead of DOMID_SELF, to
enter code paths intended for PV guest and the control domains of HVM
guests only.

This is part of XSA-237.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: George Dunlap <george.dunlap@citrix.com>

Index: xen-4.4.4-testing/xen/arch/x86/physdev.c
===================================================================
--- xen-4.4.4-testing.orig/xen/arch/x86/physdev.c
+++ xen-4.4.4-testing/xen/arch/x86/physdev.c
@@ -109,7 +109,7 @@ int physdev_map_pirq(domid_t domid, int
     if ( d == NULL )
         return -ESRCH;
 
-    ret = xsm_map_domain_pirq(XSM_TARGET, d);
+    ret = xsm_map_domain_pirq(XSM_DM_PRIV, d);
     if ( ret )
         goto free_domain;
 
@@ -254,13 +254,14 @@ int physdev_map_pirq(domid_t domid, int
 int physdev_unmap_pirq(domid_t domid, int pirq)
 {
     struct domain *d;
-    int ret;
+    int ret = 0;
 
     d = rcu_lock_domain_by_any_id(domid);
     if ( d == NULL )
         return -ESRCH;
 
-    ret = xsm_unmap_domain_pirq(XSM_TARGET, d);
+    if ( domid != DOMID_SELF || !is_hvm_domain(d) )
+        ret = xsm_unmap_domain_pirq(XSM_DM_PRIV, d);
     if ( ret )
         goto free_domain;
 
Index: xen-4.4.4-testing/xen/include/xsm/dummy.h
===================================================================
--- xen-4.4.4-testing.orig/xen/include/xsm/dummy.h
+++ xen-4.4.4-testing/xen/include/xsm/dummy.h
@@ -419,7 +419,7 @@ static XSM_INLINE char *xsm_show_irq_sid
 
 static XSM_INLINE int xsm_map_domain_pirq(XSM_DEFAULT_ARG struct domain *d)
 {
-    XSM_ASSERT_ACTION(XSM_TARGET);
+    XSM_ASSERT_ACTION(XSM_DM_PRIV);
     return xsm_default_action(action, current->domain, d);
 }
 
@@ -431,7 +431,7 @@ static XSM_INLINE int xsm_map_domain_irq
 
 static XSM_INLINE int xsm_unmap_domain_pirq(XSM_DEFAULT_ARG struct domain *d)
 {
-    XSM_ASSERT_ACTION(XSM_TARGET);
+    XSM_ASSERT_ACTION(XSM_DM_PRIV);
     return xsm_default_action(action, current->domain, d);
 }

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File xsa237-2.patch of Package xen.6121

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